1.Does routers before sending datagram to the next router check if the value of TTL is equal to 0?
2. Does router increase the value of TTL before sending datagram to the next router?
I searched everywhere for this information but I can’t find it.
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Also, speaking of routers in general, besides their main function, but can we use them for example for finding the IP address if we know computer name?
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>1.Does routers before sending datagram to the next router check if the value of TTL is equal to 0?
Yes. If the TTL is 0, the datagram is not forwarded, and an *ICMP TTL time exceeded* is returned to the source IP.
>1. Does router increase the value of TTL before sending datagram to the next router?
Routers **decrease** the TTL by one as the datagram is forwarded.
>Also, speaking of routers in general, besides their main function, but can we use them for example for finding the IP address if we know computer name?
Some routers can also act as DNS resolvers/caches – this is common functionality for home internet routers/gateways. This is not functionality that all routers have, though.
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